Devices for forming plastics material performs into plastics material containers, for example blow moulding machines, have long been known from the prior art. Heated plastics material preforms are fed to the blow moulding machines and are formed into plastics material containers, in particular by exposure to pressurised air.
In the prior art, such blow moulding machines and stretch blow moulding machines are always operated with a constant output rate. This is because the heating time and the output rate are directly linked owing to the current structure. However, the constant output rate leads to many drawbacks, in particular if the machine is installed in a “block” with subsequent machines, for example the labeling machine and/or the filler.
In this case the individual processing stations are fixedly connected to one another via transfer starwheels, and therefore so too are the output rates. However, it would often be advantageous if this block of machines could be slowed or accelerated as required, for example if faults occur in one of the subsequent units. However, this is not currently possible, in particular if the blow moulding machine is used as a lead machine.
WO 2010/015220 A1 describes a method and a device for blow moulding containers. The blow moulding machine has a stretching means which is controlled in such a way that a stretching rate directly after starting the device is predefined differently from a stretching rate in a production phase some time after operation is started.
The aim of this approach is that qualitatively high-grade containers can be produced with a short time delay before production start-up.
DE 10 2007 008 023 A1 describes a method and a device for the blow moulding of containers. The positioning of a stretching rod is pre-set with use of an electromechanical stretching rod drive, and a rotation of a motor shaft of a servomotor is transformed by a mechanical coupling means into a stroke movement of the stretching rod.
WO 2009/144664 A2 describes a system for blow moulding plastics material containers. Each blowing station comprises a drive motor which is coupled to stretching rods.
DE 101 53 045 A1 describes a method and a device for controlling a blow moulding process. In order to coordinate the control process temporarily, a current rotational positioning of the blowing wheel is measured and the corresponding measurement information is compared by an evaluation unit with pre-set switch positions for supplying and discharging the blowing fluid.
It may therefore be desirable to simplify the normal operation in particular of blocked systems which comprise a blow moulding machine, in particular to achieve a greater variability in terms of the output rate.